Polyaniline (PANI) -BFO based nanocomposite photocatalyst immobilized on liquid natural rubber as integrated adsorbents photocatalyst for removal of antibiotic Mhonishya Krishnamoorthy, Siti Fairus Mohd Yusoff, Dr. Mohamad Azuwa Mohamed, Dr. Alistair Fielding Universiti Kebangsaan Malaysia, Malaysia Ciprofloxacin (CIP) is one of the most common therapeutic drugs used widely. Untreated pharmaceutical discharge contains raw materials that are non-biodegradable and pertinacious substances tend to lower the removal efficiency of chemical oxygen demand (COD). A hydrogel-based photocatalyst was employed to remove ciprofloxacin (CIP) from wastewater using a liquid natural rubber (LNR) / bismuth ferrite (BFO) hydrogel composite with incorporation of the chromophore, polyaniline (PANI), as a conductive polymer. Maleic anhydride (MaH) was added as the crosslinking agent while acrylic acid (AAc) enhanced the gelation process of the hydrogel composite. Introducing LNR based hydrogel into PANI/BFO-based photocatalyst enables the elimination of secondary waste produced by the oxidization which is initiated by the radical sites of the hydrogel composite to end products such as H 2 O and CO 2 , which are safe to be released to the environment Response surface methodology (RSM) was used to optimize several parameters for the synthesis of the hydrogel composite and to monitor the adsorptive-photodegradation process. By monitoring the UV absorbance of CIP, without a post- treatment separation phase, the synthesized LNR-g-MaH/AA-PANI/BFO hydrogel composite showed astounding performance with up to 95% removal efficiency. The hydrogel composite was able to maintain extraction for up to ten cycles, indicating stability. It has been proposed that CIP ef uent adsorption matches the pseudo- second-order kinetic model and Freundlich isotherm model. A positive entropy number, S, in thermodynamic analysis indicates that the reaction has become more random, boosting the system’s spontaneity. Meanwhile, it is found that adsorption rate of CIP is highly dependent on pH and is under the in uence of inner sphere surface complexes as the surface was found to be net positive charge. Furthermore, CIP was adsorbed very rapidly under sunlight irradiation compared to removal under dark conditions, indicating that BFO and PANI caused photodegradation. Electron paramagnetic resonance (EPR) spectroscopy was used to monitor intrinsic paramagnetic centres during the photocatalysis. Further EPR-spin trapping experiments were used to identify reactive oxygen species generated during photolysis as evidence towards mechanism of action. The results show potential for the new hydrogel nanohybrid to improve the performance of wastewater treatment systems. References 1. Krishnamoorthy, M., Mohamed, M. A., Kaus, N. H. M., & Yusoff, S. F. M. (2022). Adsorption and Photocatalytic Degradation of Cationic Dyes over Bismuth Ferrite (BFO) Intercalated on Liquid Natural Rubber-based Hydrogel Compound. Journal of Industrial and Engineering Chemistry , xxxx . https://doi.org/10.1016/j.jiec.2022.09.035 2. Ahmad, N. H., Mohamed, M. A., & Yusoff, S. F. M. (2020). Improved adsorption performance of rubber-based hydrogel: optimisation through response surface methodology, isotherm, and kinetic studies. Journal of Sol-Gel Science and Technology , 94 (2), 322–334. https://doi.org/10.1007/s10971-020-05254-7 3. Krishnamoorthy, M., Ahmad, N. H., Amran, H. N., Mohamed, M. A., Kaus, N. H. M., & Yusoff, S. F. M. (2021). BiFeO3 immobilized within liquid natural rubber-based hydrogel with enhanced adsorption-photocatalytic performance. International Journal of Biological Macromolecules , 182 , 1495–1506. https://doi.org/10.1016/j.ijbiomac.2021.05.104
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